1. Technical Field
The present invention relates to a high performance PNP transistor and method of forming vertical PNP and NPN transistors.
2. Related Art
The ever increasing use of mobile communications is driving improvements in radio frequency (RF) communications. In particular, this expanding market is demanding lower power consumption and increased performance. One possible solution that has found many applications is bipolar complementary metal-oxide semiconductor (BiCMOS) technology. See e.g., Wilson, et al., “Process HJ: A 30 GHz NPN and 20 GHz PNP Complementary Bipolar Process for High Linearity RF Circuits,” BCTM, 1998, page 164; Onai, et al., “Self-Aligned Complementary Bipolar Technology for Low-Power Dissipation and Ultra-High Speed LSI's,” IEEE TED, 43:3, 1995, page 413; Miwa et al., “A Complementary Bipolar Technology for Low Cost and High Performance Mixed Analog/Digital Applications,” BCTM, 1996, page 185; and Chyan et al., “A 50 GHz 0.25 um . . . BiCMOS Technology for Low-Power Wireless-Communication VLSI's,” BCTM, 1998, page 128.
One problem with increasing usage of this technology, however, is that only high performance vertical NPN transistors are currently available. Current low performance lateral PNP transistors are only available with a cutoff threshold (fT) of less than 1 GHz.
In view of the foregoing, there is a need in the art for a high performance PNP transistor and a method for creating NPN and PNP transistors that both exhibit high performance.